35 comments:

Marcia Salmond
said...

I have been reading about the seastars and wonder if you have considered the waste by product of crystal meth production because tons of it have gone into those waters.Perhaps it kills some food critical to the immune systemsIs there something in the environment around the healthy ones is anyone doing grabs and loking for relationship between healthy areas or why morivirus is rampant.Is it or is just something missing from diet?

Hi, I've always like echinoderms and it's cool finding your blog, I just wish it hadn't taken a mass die off to do so. Anyhow, thank you for all the cool information, but I'm curious, has anyone been looking at planktonic larva of sea stars in the affected areas? Is this strictly an illness of adults, or is it hitting the next generation as well? It seems that a mechanical cause would be more likely to just hit the adults while an infection would go after both. Just a thought.

Darcie, thanks for your excellent question. Unfortunately, there's not really any data on the disease's effect on larvae at the moment. Since they haven't identified the agent of the disease, its hard to say whether it affects other aspects of the animal's life cycle.

This may be sort of a basic question, but one of my favorite echinoderm experiences ever was seeing vast herds of black longspine urchins (Diadema setosum, I believe) traveling together on the sea bed in Lembeh, Indonesia. I have searched the internet and can't find more than a cursory explanation of why they travel in packs. Do you have any insight into this behavior?

Autumn- I suspect that they cluster together as an aid to reproduction. Having neighbors increases the chance of their gametes being introduced to one another in the water column. But its possible there is more. I shall look into it..

Hi Chris, Fantastic blog! Hope Japan continues cool.I have an excellent plushie of an E. coli I got at the Wellcome Institute in London, but what the world really needs are FORAMINIFERA toys...BTW do you know any good foram blogs?

Hi again Chris, That was me above with the forams comment before I got the name thing right.I’ll tell you why I found your blog: I was chasing the below question. The anthropologist Baldwin Spencer went to Tierra del Fuego in early 1929 and said the sea urchins in the Murray Narrows resembles a Strongylocentrotus from Victoria (Australia). I’ve been guessing the TdelF one was Loxechinus albus cos that’s on the net as being very common there, but then what Strongylocentrotus would it be like? Any thoughts?And if so...anywhere I could access a picture?Ta!

As to your second question regarding urchins, there are no species of Strongylocentrotus which occur in Australia. However this purple speciesHeliocidaris erythorgramma superficially resembles Strongylocentrotus and was called Strongylocentrotus in the 19th century. The genus Heliocidaris was described later. some pix here: http://www.roboastra.com/hastechino/hpec36.html

I imagine Spencer chomping down on Heliocidaris in some Melbourne gentleman's club, and asking a crusty old chap from the Biology Dept what it is, and that guy gets out his MNHN books...Then many years later Spencer is in the Murray Narrows (on a rock) hassling everyone about kinship terms, and one of the local people brings him an urchin and in that moment he is transported home...

Marcia, thanks for your question. Its hard to say without seeing what you are seeing. It could be that the spines are directed against potential predators or it might be incidental. A picture might help. thanks for your interest!

We have been assigned a project to interview marine biologists to receive more information from real world scientists and I would love to ask you some questions through e-mail or this comment section. Would you be interested in answering some quick questions?

I have also noticed most of the answers to my questionnaire are in your "about me" page, which I would gladly use for my project but I would need some written permission. If you would prefer that method that is perfect for me as well.

Addison, You can use answers for your questionnaire in my "about me" page, but obviously they should be attributed correctly and be written in the proper context. Everything should be accurately reported.

Hello Chris I witnessed a population explosion of Crown of Thorns Sea Stars at Taveuni, Fiji three years ago. We were counting more than a hundred on a dive. One resort owner of 21 years said he has seen this a few times. They suddenly die off en mass when the population is so great that they are very close to each other, as if some deadly plague of a bacteria or a fungus is spread about. He suggested that the disease might spread by contact when the Crown of Thorns population gets dense enough. Do you have any insight into a possible nature of the disease?Mike www.mikescotlandscuba.com

Hi Mike, There has been a long history of ideas regarding the Crown of thorns population plague outbreak phenomena. There have been some 5 or 6 major theories that become popular every few years. The current one is that larval numbers are enriched by run off from terrestrial or some other source leading to enhanced recruitment of adults.

one of these days I will have to write a short summary of the various schools of thought.

The die-off dynamic is one that I've not hear before but its often difficult to assess localized versus widespread outbreaks. interesting account. thanks!

Hi, the COTS are an interesting animal alright. I have been studying them on and off for a while and am wondering where they sit in the hierarchy of most fecund starfish? They would have to be close to the top, but what about things like Pycnopodia and other large multi-armed starfish? Does anyone out there know of published data on some of these species. The max for COTS based on Pratchett's recent review is 65 million!

This statement in the Wikipedia article on echinoderms piqued my curiosity:

"Echinoderms are also the largest phylum that has no freshwater or terrestrial (land-based) representatives."

To your knowledge, is this claim accurate? Obviously, the negative cannot be proven. But is this a generally accepted observation?

After reading that, I've wondered about the possibility of a non-marine echinoderm (NME). Does the physiology of the phylum require a marine environment? Have NMEs been found but cataloged incorrectly? Does the fossil record suggest there may have been NMEs at some time in the past? So many questions!

(I'm a retiree with no background in biology who is interested in this puzzle.)

Hi Mr. Harris, That statement is VERY accurate. Echinoderms do not occur in marine settings. Some cryptic species such as brittle stars can tolerate brackish water (i.e. mixed sea & fresh) but to date, no freshwater echinoderms have ever been found.

Their absence from these habitats is thought to lie largely because of the absence of water-regulating organs, such as the kidney. All echinoderms are essentially filled with seawater to survive. They actually use it as circulatory fluid.

Echinoderms have been documented since the 18th Century and with no evidence of freshwater occurrence. And more importantly no evidence that they can tolerate freshwater. Starfishes are often found dead after rainstorms on some coasts. Sponges and many other animal groups have successfully navigated the osmoregulatory gauntlet and made the invasion.. but there's no evidence that echinoderms have.. Their long success story in the oceans is a conservative one.

I have read about Linckia diplax species' exceptional ability to in some cases reproduce from a single limb with no central disc. They are said to be able to produce a small central disc and then grow from this into a new starfish over several months. My question is, how can this single limb with no central disc survive and how can it feed to gain the energy that would be needed to regenerate the disc without the stomachs?

About Me

I pursue starfish related adventure around the world with a critical eye and an appreciation for weirdness.
Support has been courtesy of the National Science Foundation but the views and opinions presented herein are mine and do not reflect the opinions of them or any affiliated institutions.
Need to hire an invertebrate zoologist/marine biologist? Please contact me!